Senate Democrats, wary of the government being pulled deeper into the Washington swamp, are demanding tax returns from President-elect Donald Trump’s prospective cabinet members–before they begin confirmation hearings.

Top Democrats on several Senate Committees held a press conference this morning to announce the new push. Cabinet nominees must provide tax returns to the relevant committees ahead of their confirmation hearings.

Using his own campaign rhetoric to frame the issue, Senators told Trump “Don’t Rig the Cabinet.”

Another sign said “Donald Trump Keeps D.C. Swampy.”

“During his campaign, Donald Trump said he would drain the swamp. Instead, he’s flooding it with America’s wealthiest elites,” said Sen. Debbie Greer Stabenow, a Michigan Democrat.

“His nominees for his cabinet are millionaires and billionaires who are part of the very establishment that Donald Trump campaigned against. He told working people in Michigan he wouldn’t do that,” she added.

Without seeing tax returns, it’s impossible to know if his nominees have conflicts of interest from financial dealings that would influence their decisions, Stabenow said.

She called Trump’s nominees an unprecedented collection of wealthy insiders and big money interests.

The issue is a sore point growing out of the election when then-candidate Trump refused to release his tax returns. They would have provided a significant amount of detail about his financial holdings and potential conflicts of interest.

Almost a month since the election, Trump still refuses to release his returns, citing the same reason. He claims they are under audit, even though the IRS said during the campaign an audit wouldn’t bar releasing his returns.

Democratic rival Hillary Clinton released 32 years of tax returns, following a precedent going back to the 1976 election. Every president since then has released their returns while campaigning for the office.

“We still have questions how he will keep his business dealings and the office of president separate,”

Stabenow reminded Trump that he now works for the people of the United States, not “the special interests of his family and wealthy friends.”

“When President-elect Trump refused to release his tax returns during the campaign a whole lot of us wondered why?” said Sen. Patty Murray, D-Washington.

“What was he trying to hide from voters, especially given his long record of failed business deals, conning students and workers, tall tales of his charitable donations [and] so much more?” she said.

“Which foreign governments and banks does he own money to? Does he pay any taxes? And, how do the tax policies he campaign on benefit him, his partners, and his businesses. And, what other conflicts of interest does he have?”

Keith Girard has 30 years of experience as an award-winning reporter, editor-in-chief, and senior media executive. Keith’s career began in Washington, D.C., where he was a reporter for The Washington Post and a contributing editor for Regardie's and Washingtonian magazines. He also worked as a writer/producer in CNN's Washington Bureau and has written one book on the U.S. Marines in the Gulf War.